126 Prof. H. A. Nicholson — New Devonian Fossils. 



zone. The frond is celluliferous on both sides, forming two continuous 

 layers, their proximal ends or bases being placed back to back, but 

 separated by a delicate calcareous membranous or laminar axis, which 

 exhibits numerous close-set transverse curved strife. From six to 

 ten cells occupy the space of a line measured diagonally, whilst the 

 form of the cell-mouths is oval or circular, and the cells do not 

 appear to be arranged in distinct rows separated by elevated strise. 



Glathropora intertexta is very closely allied to C. frondosa, Hall, 

 a beautiful and not very rare species from the Niagara Limestone. 

 It is clear, however, that Hall has included two species under this 

 name. One of these, comprising all the specimens which I have 

 collected personally from the Niagara Limestone, is very readily 

 distinguished by the exceedingly small size of the fenestras (see 

 Pal. N.Y. vol. ii. pi. xl. B. fig. 5 b), which have a diameter of only 

 about half a line, and look simply like little oval or circular per- 

 forations in the membranous coencecium. The cells, alsoi^ are 

 remarkably long and narrow, and about fourteen of them occupy 

 the space of one line measured transversely. There can be no 

 question as to the entire distinctness of this from C. interiexia, and 

 I should be disposed to consider this as the type of C. frondosa^ 

 Hall. The other forms included by Hall under G. frondosa resemble 

 our species in their proportions and in the size of the fenestrse 

 (see Pal. N.Y. vol. ii. pi. xl. B. fig. 5 a) ; but in the absence of any 

 sufficiently detailed description, it is impossible to say that they are 

 absolutely identical with G. intertexta. Should this, however, by 

 an actual comparison of specimens, prove to be the case, I should 

 propose that the name of C. frondosa should be restricted to the 

 specimens with small fenestrge and minute close-set cells ; whilst the 

 name of G. intertexta should be applied to the undoubtedly distinct 

 examples with large fenestrge and comparatively large cells. In 

 any case, as before remarked, both of these species of Glathropora 

 might without impropriety be regarded as nothing more than re- 

 ticulated Ftilodictyoe. 



Locality and Formation. — Corniferous Limestone, Jarvis, Township 

 of Walpole. (Collected by Mr. George Jennings Hinde.) 



EXPLANATION OF PLATE VI. 



Fig. 10. — Productella Eriensis, Nich. a. Exterior of the dorsal valve, partially ex- 

 foliated, enlarged, b. Cast of the ventral valve of a rather larger example, 

 enlarged, c. Interior of the dorsal valve enlarged, d. Cast of the ventral valve 

 of an example with extended ears, enlarged. Fi't)m the Corniferous Limestone. 



Fig. 11. — Leiorhynchus Huronensis, Nich. a. Dorsal view. h. Ventral view of the 

 same. c. Side view of a larger individual. From the Hamilton Group. 



Fig. 12. — Tainopora penniformis, 'Nich. a. Fragment, of the natural size. b. Trans- 

 verse section of the same, enlarged and partly conjectural, c. Fragment 

 enlarged, d. Fragment still further enlarged, showing the central keel and 

 prominent cell-moutlis. Frcim the Hamilton Formation. 



Fig. 13. — Tceniopora exigua, Nich. a. Portion of the frond, natural size. b. The 

 same enlarged, the portion drawn in outline being conjectural, c. Portion 

 of the same still further enlarged. From the Hamilton Group. 



Fig 14. — PtUodictya Mteki, Nich. a. Porti"n of the frond magnified to show the 

 brHnching and ihe longitudinally striated axis. b. A fragment enlarged still 

 further to show the form and arrangement of the cells, c. Transverse 

 section enlarged. From the Corniferous Limestone. 



(To be continued.) 



